This invention relates to a time release bolus for administering a medicament or nutrient substance to a ruminant. The bolus is designed such that the contents thereof are released therefrom into the ruminant over an extended period of time. In this way, controlled amounts of nutrients and/or medicaments can be administered to the ruminant over a given time period so that daily or a very short term examination and treatment of the ruminant is substantially eliminated.
It is well known in the art to introduce into ruminants nutrients, medicaments, drugs or other dietary supplements by means of a system whereby the ruminant ingests a bolus which remains in, for example, the rumen thereof and dispenses its contents over a period of time. It is cumbersome and labor intensive to introduce into the daily food intake of such ruminants the required amount of any drug, medicament nutrient or other substance. A controlled time release bolus therefore has the significant advantage of providing the animal with nutrients and medicaments which will be released into the body over a period of time. In general, substances and nutrients beneficial to the animal can be included in all such time release boluses, while specific medicaments or substances required by a particular animal or group of animals in a given area may be included as well. In this way, any deficiencies in a particular area, or infectious agents peculiar to a specific location, can be included in the time release bolus, and the animal will receive appropriate supplements to dietary deficiencies, or medicaments or drugs which are able to counteract infections to which a particular animal, or a particular region, is susceptible.
A wide variety of devices for administering substances to ruminants are known in the prior art. For example, Laby (U.S. Pat. No. 3,844,285) discloses a device having a body portion containing the substance and adapted to assume a first configuration in which it can be administered per os to the animal, and thereafter changes into a second configuration to prevent or hinder regurgitation while in the rumen. Drespack (U.S. Pat. No. 4,220,153) teaches a delivery system for controlling release of chemicals using a device having a wall formed of a porous fabric material which is in contact with a reservoir containing the chemical. Brewer (U.S. Pat. No. 4,228,149) discloses a sustained release composition wherein a medicament is dispersed in a sheet of water insoluble polymer. The sheet may be constrained in a position which allows oral administration, namely, by rolling the sheet in a strip of paper which loses its adhesive properties once introduced into the rumen. The sheet unfolds, at the same time preventing or hindering regurgitation thereof.
Laby (U.S. Pat. No. 4,251,506) shows a controlled release device for administering active agents to ruminants comprising a tubular body adapted to receive a precast cylindrical plug of therapeutic composition. A plunger, in conjunction with a helical spring, biases the plug towards an opening of the tubular body. The opening is a restricted one, resilient projections controlling the exit of the precast cylindrical plug from the tubular member. The device further includes a pair of resilient arms extending away from the tubular body. The arms may, however, adopt a configuration whereby they abut the tubular member, and with this arrangement the device may be administered per os to the ruminant. Once in the rumen, the arms project outwardly at an angle to the tubular body thereby hindering or preventing regurgitation of the device.
Guerreio describes a bolus having a fine mesh completely encasing the medicament. A heavy metal core may be provided. Bagnall (U.S. Pat. No. 4,564,363) teaches a device for effecting delayed release of an active ingredient which is contained within a container, the device comprising a removable closure and an electrical control circuit for removal of the closure at a designated time to release the active ingredient. Laby, in U.S. Pat. No. 4,623,345, describes a capsule having two body portions of magnesium or an alloy thereof pivotally connected to each other for movement between a relatively small cross-sectional configuration in which the capsule can be administered per os into the rumen, and a relatively larger cross-sectional configuration which resists regurgitation. Laby, in U.S. Pat. No. 4,687,480, teaches a capsule comprised of a tubular body, a cap at one end and an access opening at the other. Wings are provided and are movable between a first position away from the tubular body and a second position against the tubular body. The shape and structure of the wings enable them to be applied closely the tubular body to permit easy introduction into the rumen. At the access open end, an annular disk is provided, and a plunger and coil spring bias tablets towards and out of the opening for introduction into the system of the ruminant.